31820 -- U.S. ZIP code Municipality (1990): MIDLAND, Georgia All ZIPs for this municipality (1990): 31820 Population (2000): 5013 Housing Units (2000): 1816 Land area (2000): 38.358644 sq. miles (99.348428 sq. km) Water area (2000): 0.352565 sq. miles (0.913139 sq. km) Total area (2000): 38.711209 sq. miles (100.261567 sq. km) Located within: Georgia (GA) Location: 32.566197 N, 84.841223 W